Process for refining glyceridetype oils



March 14, 1939. B, H, THURMAN 2,150,733

PROCESS FOR REFINING GLYCERIDE-TYPE OILS Filed July 2, 1937 a do /6 /4A5 & k; x

5%,? i: iii A9 ld i? mai [xv ve/v TOR 55mm M/N H. mum/m xv a y be 43HARA/o, KmcH, FO67'ER d- HARR/s Patented Mar. 14, 1939 UNITED STATESPATENT OFFICE Benjamin H. Thurman, B'ronxville, N. Y., assignor toRefining, Inc Reno, Nev., a corporation of Nevada Application July 2,1937, Serial No. 151,702

28 Claims.

My invention relates to a novel method for refining glyceride type oils.

Such refining has for its purpose the removal of various impurities fromsuch oils. In general, it has two aspects, seeking in the first place toneutralize and remove free fatty acids with a minimum of saponificationof neutral oil and, in the second place, to produce a refined oil ofsatisfactory color, evident either from the refined oil when firstseparated or from this oil after subiection-to conventional bleachingsteps.

It is an object of the present invention to provide a novel method foraccomplishing both neutralization and color reduction by use of arefining reagent, for instance caustic soda, caustic potash, usually inaqueous solutions, or other alkaline solutions, used in excess of thatamount theoretically required to completely react with the free fattyacids.

Much of the refining of vegetable oils is now being performed bycontinuous processes. With most glyceride type oils, suchcontinuous-proceases are entirely satisfactory. I have found, however,that difilculty is sometimes encountered in applying the process tovarious crudes and still producing refined oils of satisfactory color.For instance, Brazilian or Egyptian cottonseed oil or certain Americancold-pressed oils give difiiculty in this respect and the presentinvention has been found very satisfactory in treating such oils. Also,the refining of the so-called slowbreaking" oils is materially improvedby the present invention. All such oils, and others of similar nature,are herein referred to as "difiicult oils".

It is an object of the present invention to refine suchoils by use of anexcess of the refining reagent and to condition the oil bymaintainingthe excess reagent in contact therewith, after neutralizationof the free fatty acids, for an increased time sufilcient to produce adesired bleach of the oil. I

A further object is to maintain the oil during this additionalcontacting period under such conditions as to prevent substantialseparation of the constituents, particularly to prevent thegravitational separation of all or any substantial part of the soapstock or foots resulting from the reaction between the free fatty acidsand the refining agent. The mixture may be maintained under thesuperatmospheric pressure conditions during this period of additionalcontacting though this is not always essential.

The invention also finds application to the refining of glyceride typeoils of a 'character which can be refined to produce oils ofsatisfactory color by the continuous process now known in the art. It isthus not limited in all of its aspects to treatment of a di ficult oil.For instance, other novel concepts of the invention reside in applyingheat to such portions of a refining system as will facilitate separationof the refined oil and improve the operation of the process generally. I

It is another object of the present invention to mix proportionedquantities of a glyceride type oil and a refining reagent and to movethe resulting mixture through a conditioning zone or chamber atrelatively low velocity preparatory to separation of the refined oil,and preferably to maintain the mixture in this conditioning zone orchamber under such conditions that the foots will not substantiallyseparate therefrom.

Further objects and advantages of the invention will be made evidenthereinafter.

While the process and apparatus are applicable to the refining of allglyceride type oils, the following description will have particularreference to the refining of cottonseed oil of the difficult typ In thedrawing, I show diagrammatically a simple form of apparatus by which theprocess can be carried on.

In the illustrated apparatus, the numeral I indicates a proportioningmeans, 2 a mixing means, 3 a conditioning means, 4 a heating means and 5a separating means.

The function of the proportioning means I is to deliver to the mixer 2proportioned quantities of the glyceride type oil and the refiningreagent. Preliminary tests on the oil being. refined will indicate thefree fatty acid content and an amount of refining reagent is used totake care of the amount theoretically necessary to completely react withthe free fatty acids and leave an excess. This excess will desirably beabout the amount used in conventional refining processes.

Any suitable proportioning means can be used in this capacity, theembodiment shown including an oil pump it and a reagent pump llrespectively withdrawing oil and refining reagent froin tanks l2 and I!through pipes i4 and II and' delivering same to the mixing means 2. Suchpumps may be of the piston type and may be interconnected by a variablespeed means I, being driven by a suitable drive means li or variousother control means can be used to vary the proportions introduced intothe mixing zone. If desired, the oil or the reagent, or both, may bepreliminarily heated before being mixed. This may be accomplished byapplying heat in the tanks l2 and II, or by the interposing of heatersII and II in the pipes ll and II. Heaters of the coil type will be foundvery satisfactory and a heating medium can be circulated through acontainer surrounding such coils in any well known manner.

If continuous mixing is to be used, the mixing means 1 will give verysatisfactory results. The function of the device shown is to mixintimately the proportioned streams of oil and reagent deliveredthereto. Various mixers can be used in this regard which rely uponmechanical agitation, turbulence or other mixing actions. I have foundit entirely satisfactory to inject one liquid into a flowing stream ofthe other. For instance, the mixing means 2 may include a shell 20providing a mixing zone and the reagent can be introduced into a flowingstream of the oil moving in this zone. This injection, together with theturbulence in this mixing zone, is sufhcient to quickly form an intimatemixture and disperse the reagent in line droplets in the oil. Nosubsequent mixing of a more violent nature is necessary.

The reaction between the reagent and the free fatty acids is very rapidand most of the free fatty acids will be neutralized in the mixing zoneor during flow therefrom and prior to reaching the conditioning means 3.However, the colorremoving reaction between the color impurities and theexcess reagent usually proceeds more slowly. With oil such as Brazilian,Egyptian or American cold-pressed cottonseed crudes, this color-removingreaction is quite slow and with these, as well as with certainslow-breaking oils, it is desirable to prolong the contact time betweenthe excess reagent and the oil.

The function of the conditioning means 3 is to provide a zone in whichthe mixture will be conditioned, one factor in this conditioning beingsuch prolonging of the aforesaid contact time between the excess reagentand the oil. In refining e difficult oils, the mixture may remaintherein for several minutes for, with oils such as mentioned above, Ihave found that satisfactory colors can be obtained by prolonging thetime of contact of the excess reagent and the color impurities in themixture. With the foreign oils mentioned and with American cold-pressedoils and with most slow-breaking oils, I have found it desirable to usea total contacting time, between first mixing and separation, of threeminutes or more and often five minutes or more. This time will vary withdifferent oils and invariable ranges cannot be set forth in view of thedifferent characteristics of different oils and the seasonal variationsthereon, as well as variations due to different procedures in pressingthe seeds to obtain such oils. In general, it can be said that the totaltime of contact should be sufiicient to produce an oil of the desiredcolor.

In the preferred mode of operation, the contacting time in theconditioning means 3 is longer than the mixing period in the mixingmeans 2. In fact, I prefer to intimtely mix for a very short period oftime and remove the mixture from the mixing zone about as soon asneutralization of the free fatty acids is complete. The mixture thusremoved from this zone will then include oil, foots, color impurities,and all or a major portion of the excess refining reagent.

I have found that this conditioning of the mixture can best be performedin a conditioning zone or chamber in which the mixture exists under suchconditions that the foots are not permitted to gravitationally separatetherefrom. It is desirable that the foots be maintained substantiallyuniformly distributed in the oil during this conditioning period andonly such turbulence is desirable as will be sufficient to maintain aproper distribution of the foots and the excess refining reagent in theoil, with a consequent maintenance of the contact between the excessrefining reagent and the oil. It is not desirable to agitate the mixtureviolently during this conditioning period, for such action would tend tobreak up the foots, thus making the subsequent steps of the process moredifllcult to perform. Turbulence or agitation in this conditioning zone,however produced, will thus be desirably less than in the mixing zone,for it is neither necessary nor desirable that violent mixing orexcessive turbulence should be used during the conditioning. Inaddition, if the conditioned mixture is later moved as a stream to theseparating means i, it will usually be found desirable to use aconditioning zone which is larger in cross sectional area than theconduit through which the conditioned mixture flows to this separatingmeans. This permits conditioning under decreased velocity if the mixtureis continuously delivered to and withdrawn from the conditioning zone.

This conditioning can well be accomplished according to the presentinvention by use of a vertically-extending chamber or zone 26 formed bya container 26 which is preferably, though not necessarily, confinedfrom the atmosphere so that superatmospheric pressures can be maintainedtherein sufficient to force the mixture through the subsequentequipment. If open to the atmosphere, gravitational flow can be reliedupon to move the conditioned mixture to the separating means. Themixture is delivered from the mixing means 2 through a pipe 21positioned to introduce the mixture into either the upper or lowerportion of the container, the latter being preferred in flowing thismixture upward in this container.

In some instances, the vertical movement of the mixture in the chamber25 may be sufficient to maintain the foots uniformly distributed.However, I have found that the foots will tend to deposit on the innerwalls of this chamber and, for the purpose of removing these depositedfoots, I prefer to utilize some means in this chamber moving adjacentsuch walls. By way of example, a series of superimposed scrapers 30 maybe used to rotate adjacent, or in contact with, the inner cylindricalwall of the chamber 25, the various series being so disposed thatsubstantially all portions of this wall are cleaned by movement of thescrapers. Each scraper may be mounted on a relatively small rod 3| andthus attached to a shaft 32 which is suitably journailed and whichextends through a stuffing box 33. Gear means 34 may be used to drivethese rotatable units but the speed of rotation should be quite slow. Aspeed of about 75-400 R. P. M. will be found satisfactory. If violentagitation is used during the conditioning step, a tight emulsion will beformed which is not readily susceptible to centrifugal separation.Further, any such violent agitation will tend to break up the particlesof foots and defeat any tendency for the foots to begin to agglomeratein this chamber. While one function of this rotatable structure is toremove from the walls and return to the oil foots which may clingthereto, it will also serve arsonaa as a turbulence-producing meanswhich establish'es such mild turbulence as will maintain the footsuniformly suspended. Ingeneral, it can be said, however, that theturbulence in this conditioning chamber should be relatively less thanis required in the mixing zone, and the desired turbulence can beinduced by flow conditions or by use of a rotating element, or by both.

Such conditions maybe simulated or duplicated by continuous flow of themixture from the mixing zone through a conditioning chamber formed by apipe or coil suitably designed. Such a pipe or coil will preferably beof smaller cross sectional area than the container 2 and considerablylonger. It may be so designed that the incidental turbulence due tostream flow of the mixture therethrough will maintain the footsuniformly distributed and prevent substantial deposition thereof on thewalls. For example, a coil having a diameter of about zt inches will befound satisfactory if suitable velocity is maintained therein. Coils orpipes of larger or smaller diameter may be used if proper velocityconditions and incidental turbulence are maintained. The length of suchan elongated conditioning zone should be such as to give sufficientincrease in contact time similar to that obtained by the use of thelarger conditioning chamber shown in the drawing.

This conditioning is usually facilitated if the mixture is at somewhatelevated temperature, though heat applied to the conditioning chambercan often be dispensed with, particularly where pre-heating of the oiland reagent, or

either, is used. However, the system shown permits heat to be suppliedto the container 26, if desired, as by a jacket 38 therearound andthrough which a suitable heating medium may be circulated.

The conditioned mixture is preferably withdrawn from the opposite end ofthe chamber 25 from which it is introduced as through a pipe llcontaining a valve 39. By closing the valve 39 and opening a valve 40,this mixture will flow through a pipe 4| to an intake pipe 42 of theseparator 5. By closing the valve 40 and opening the valve 39, theconditioned mixture will flow through the heating means 4 and thence tothis pipe 42 preparatory to separation. Depending upon how much heat hasbeen added before the conditioned mixture flows through the pipe SI andupon how much heat is added in the separating means 5, the heating means4 can be used or dispensed with as the process may dictate.

In the embodiment illustrated, the heating means 4 includes a shell 44in which is positioned a pipe coil 45 intaking from the pipe 38 anddischarging into the pipe 42. A heating medium may be circulated throughthe shell 44 or a burner 46 may be positioned in the lower end thereof,receiving a fluid fuel through a pipe 41 and discharging products ofcombustion upward around the coil 45 in heating relationship. A suitableadJustable thermostat 48 may control the supply of fuel to the burner inresponse to the temperature of the reaction products discharged from thecoil 45. Such thermostats are well known and need not be specificallydescribed.

The coil 45 provides an elongated passage of relatively small ,crosssectional area, while the chamber 25 provides a space of considerablylarger cross sectional area. Thus, the velocity of the mixture in thechamber 25 will be relatively low and the velocity through the elongatedpassage defined by the coil 4| will be relatively higher and the samedifferential velocity can exist if the conditioning chamber is formed bya coil or pipe though this is not, in all instances, necessary. Thisincrease invelocity is often desirable, particularly if heat is suppliedduring passage through the coil 45. In addition, such movement throughthe coil 45 facilitates agglomeration of the foots preparatory tocentrifugal separation. With the slow breaking oils, it is oftendesirable to operate the system so'that the break occurs primarily inthe coil 45 or in the pipe 4|, as distinct from the conditioning chamber2|, though this is not essential on this or other types of oils,particularly if pre-heating is used.

The function of the separating means I is to receiveand separate refinedoil from the reaction products delivered thereto. The embodimentillustrated showsi. single centrifuge in this regard though, usually,the stream is divided between a plurality thereof. Conventionalhigh-speed centrifuges may be used in this capacity, respectivelydelivering refined oil and foots through spouts $2 and 53. However, useof a centrifuge, such as shown in the co-pending application of BenjaminClayton, Serial No. 34,258, entitled Process for refining glyceride oil,now Patent No. 2,100,277, granted November 23. 1937, is particularlyadvantageous in the present process and produces con' tinuous operationover long periods of time, better-colored oils, lower refining losses,etc., and improves the process throughout. Such a centrifuge is of thetype in which heatis applied to the zone of centrifugal separation. Forexample. steam may be introduced into the centrifuge through a pipe 54as controlled by a valve 5! to surround the rotating bowl thereof. Heatthus applied to the centrifugal zone by conduction through the bowlinsures smooth and continuous movement of the soap stock or foots alongthe outer wall of the bowl and prevents accumulation of deposits on thiswall, thus overcoming a source of difficulty in other types ofcentrifugal equipment which must be shut down every few hours to cleanthe bowl. It permits discharge of the re fined oil and soap stock atdifferential temperature if desired and can be utilized to overcome therefrigerating effect in the centrifuge.

Another method of applying heat to the zone of centrifugal separation isto introduce a suitable heating medium into the reaction products asthey flow into the centrifugal zone, for instance, or hot fluid can beintroduced into the pipe 42 immediately ahead of the centrifuge througha pipe 51 including a valve 58. A quick increase in temper ature byapplying heat to the reaction products before centrifugal separation, orby applying heat to the centrifuge itself, makes possible the use oflower temperatures in the preceding equipment and results in decreasedrefining losses.

It will be clear, however, that heat may be applied'at various pointsalong the system. For instance, the oil, or the oil and the refiningreagent, may be pre-heated before being mixed. The mixture may be heatedduring conditioning by circulating a heating medium through the jacket36. Heat may also be applied during flow through the heater 44, or itmay be applied more directly to the zone of centrifugal separation byheating the bowl of the centrifuge or introducing a heating mediumthrough the pipe 51. It is within the scope of the present invention toapply depend upon the heat subsequently added, the place or places whereit is applied and upon the haracteri ics of the particular oil to berefined. If heat is applied to subsequent portions of the system, it isnot essential to pre-heat the oil except as an incidental amount of heatmay be beneficial in putting the more viscous oils, such as variousfats, into better condition for pumping. Thus, the oil can be introducedinto the system at substantially room temperature or somewhat above, ifsubsequently heated in the conditioning chamber 25, the coil ll or in orat the centrifuge itself. However, in many instances, unexpected resultsaccrue from using higher pro-heating temperatures and, in this respect,heating of the condltioning zone 2! or the coil it may often bedispensed with. Temperatures as high as 160 1". or higher may be-appliedto the oil before introducing the refining reagent thereinto and, ifdesired, similar pre-heating temperatures may be applied to the refiningreagent itself though, in most instances, it is quite satisfactory tointroduce this reagent at a temperature which is lower than that of theoil. If the temperature of the refining reagent is higher than that ofthe oil, it will serve to additionally heat this oil in the mixer 20.Very satisfactory treatment can be obtained by thus pre-heating the oilor the refining reagent, or both, and moving the mixture through theconditioning zone 25 and thence either directly to a centrifuge throughthe pipe H or through the coil II. In either instance, the operation isdistinctly improved by the use of a centrifuge provided with a heatedbowl. Also, in either instance, heat applied to the conditioning zone 28or the coil 45 may be dispensed with if the pre-heating temperature hasbeen appropriate. In other instances, sufficien heat may be applied tothe conditioning zone 2! or to the coil l, or to both, to maintain thetemperature therein substantially the same as in the mixing zone.Somewhat better results will sometimes be obtained by flowing theconditioned mixture through the coil ll before reaching the centrifuge,rather than by-passing this coil by how through a shorter path definedby the pipe 4 I. However, in either instance, flow through this coil orthrough the pipe ll may additionally condition the mixture for eilicientcentrifugal separation of the foots from the oil, for example, byfurther agglomerating the particles of foots yet maintaining theseuniformly dispersed so that the mixture reaching the centrifuge is of auniform character and actual gravitational separation of the foots isprevented before reaching this centrifuge.

In other instances, pro-heating can be dispensed with and the mixturecan be formed at substantially room temperature, or somewhat thereabove.Here again, the use of a centrifuge providing a heated bowl isadvantageous, irrespective of whether additional heat is applied in theconditioning zone 25, the coil 4 or adjacent the centrifuge. It will beunderstood that, in this mode of operation, heat may be applied at oneor more of these points and that the coil ll can be by-passed withsuccess in many instances by proper design of the equipment and byproperly-controlled addition of heat. In other instances, thetemperature can be maintained relatively low until fiow through the coilof the heater, no increase in temperature taking place in theconditioning zone.

By way of illustration, the process has been used to refine deterioratedBrazilian crude cottonseed oil at a rate of pounds per minute to producea bleachable grade of oil. Mixing was equipment.

obtained by introducing the refining reagent into a stream of oil movingthrough the mixing zone and the time of such mixing was very short,being only a few seconds. The container Iii of the conditioning meanswas eighteen inches in diameter and five feet high and the mixtureremained therein about six minutes. No heat was supplied at this pointin this test, nor was the oil preheated.

Ihe conditioned mixture was heated during fiow through a sectional coilformed of one and one-half inch pipe and having a total length of about550 feet. The resulting reaction products were introduced into thecentrifuge at a temperature of about -l45 F. and steam was used forheating the exterior of the bowl. The tempera ture of the refined oildischarged from the centrifuge was approximately the same as theentering reaction products and the foots discharged at a temperatureapproximately 10-20 F. hotter. The system operated continuously andproduced a bleachable grade of refined oil. The color of the oil issuingfrom the spout 52 was 35 yellow, 7 red, and readily bleached to 20yellow and 2.5 red when a bleaching material was added thereto andsubsequently filtered therefrom.

It will be understood that the invention is not limited to continuousintroduction and withdrawal from the conditioning chamber 25. In someinstances, it is possible to utilize a plurality of such chambers,filling them successively with the mixture and successively withdrawingthe conditioned mixture therefrom, this mixture moving either directlyto the centrifuge or being first passed through a heating zone, such asis defined by the coil 4. In this manner, any desired contact time canbe obtained and, if desired, the chambers may be open to the atmospherethough a closed conditioning chamber is preferred. If such amulti-chamber system is used, it is desirable to maintain suchturbulence in the conditioning zone that the foots remain substantiallyuniformly distributed therein and, if superatmospheric pressure ismaintained therein by the proportioning pumps, this pressure can be usedto force the conditioned oil through the subsequent However,substantially atmospheric pressure can be used during the conditioningstep and the pressure subsequently raised to force the conditionedmixture therefrom, or gravity-induced fiow relied upon to move theconditioned mixture to the centrifuge.

Various changes and modifications can be made in the process andapparatus, as will be apparent to those skilled in the art, withoutdeparting from the spirit of this invention as defined in the appendedclaims.

I claim as my invention:

1. A process for refining glyceride type oils to remove impurities suchas free fatty acids and color impurities, which process includes thesteps of: forming a mixture of proportioned quantities of said glyceridetype oil and an alkaline refining reagent capable of reacting veryrapidly with said free fatty acids to form foots and used in excess ofthat amount theoretically required to complete reaction with the freefatty acids, the excess being available for reaction'with said .colorimpurities to produce a mixture containing oil, foots, color impuritiesand the excess of said refining reagent; introducing said mixture into arelatively wide stirring chamber and therein maintaining a relativelylarge volume thereof under such conditions of turbulence to maintain thefoots uniformly distributed in the oil while avoiding turbulence in2,150,788 excess thereof and for a sufficient time and at a sufficienttemperature to condition the mixture for the act of centrifugalseparation and to eflect substantial color reduction; flowing a streamof this conditioned mixture into a zone of centrifugal separation; andthere separating the foots from the oil while applying heat to the zoneof centrifugal separation sufficient to condition the mixture for saidcentrifugal separation.

2. A process for refining glyceride type oils to remove impurities suchas free fatty acids and color impurities, which process includes thesteps of: neutralizing said free fatty acids by adding to and mixingwith said oil an alkaline refining reagent capable of reacting with saidfree fatty acids to form foots and used in excess of the amounttheoretically required to neutralize said free fatty acids, the excessbeing available for reaction with said color impurities thus producing amixture containing oil, foots, color impurities and the excess of saidrefining reagent; con ditioning this mixture for centrifugal separationin a relatively large conditioning zone by applying heat thereto whilemaintaining therein only such turbulence as will prevent substantialseparation of said foots and continuing this conditioning until saidcolor impurities have reacted with said excess of the refining reagent;moving a stream of the conditioned mixture through an elongated passageto a separating zone; applying heat to said mixture during this flowthrough said elongated passage; and centrifugally separating the footsfrom the oil in said separating zone by subjection to centrifugal forcewhile the mixture is at a temperature sufficient to facilitate suchseparation.

3. A process for refining a glyceride type oil to remove impurities suchas free fatty acids and color impurities, which process includes thesteps of: continuously mixing proportioned streams of said oil and analkaline refining reagent capable of very rapidly reacting with the freefatty acids in said oil to form foots and used in excess of that amounttheoretically required for such reaction with the free fatty acids;alternately discharging the mixture thus formed into a pair ofconditioning chambers; and retaining said mixture in said chambers for asuflicient time and under sufficient temperature conditions to insurebreaking of the emulsion and to effect substantial color reduction;maintaining conditions in said chambers such that said foots remainsuspended in said mixture; alternately withdrawing the mixture from saidconditioning chambers to form a continuously moving stream; andsubjecting the mixture in said stream to a centrifugal force tocontinuously separate refined oil therefrom while maintaining anemulsion breaking temperature during such separation.

4. The process of refining animal and vegetable oils containing freefatty acids which comprises mixing an alkaline refining agent with saidoil to neutralize the free fatty acids and form a mixture including soapstock, heating a relatively large vessel containing a relatively largebody of said mixture, during agitation thereof, to a temperaturesufficiently high to break any emulsion which may exist, thereby tocondition the mixture for the act of centrifugal separation of the soapstock from the oil, continuing the agitation of such relatively largebody of the mixture at a rate sufficient to maintain the mixturesubstantially uniform and to prevent stratification of said soap stock,but at a rate insufiicient to break up the particles of the soap stock,withdrawing a stream of the thus conditioned mixture from saidrelatively large vessel, while the agitation continues, and deliveringthe same to a centrifugal separator and continuously centrifugallyseparating said soap stock from the oil of said stream while the mixtureis conditioned for such separation.

5. The herein described process of refining animal and vegetable oilswhich comprises the steps of mixing the oil with an alkaline reagent ata sufficiently low temperature to permit the formation of an emulsionand the substantially complete neutralization of the-free fatty acidswith the resultant formation of soap stock, subjecting a relativelylarge body of said mixture, in a relatively large vessel, to an elevatedtemperature, sufficiently high to break the said emulsion, thereby tocondition the mixture for the act of centrifugal separation of the soapstock therefrom, subjecting the mixture in said vessel to mildmechanical agitation after the application of heat thereto, sufficientto cause such turbulence as will maintain a proper distribution of thefoots in said oil, without such violent agitation as would tend to breakup the foots in a difllcultly separable condition, therebymaintainingthe mixture in a separable condition, while continuously withdrawing thesame from the vessel and introducing it to a centrifugal separator forthe continuous separation of the soap stock therefrom while the mixtureis conditioned for such separation.

6. A process for refining animal and vegetable oils which comprises thesteps of mixing an alkaline refining reagent with said oils to effectsubstantially complete neutralization of the free fatty acids containedin the oil and the resultant formation of soap stock, maintaining a.relatively large body of the mixture in a relatively large receptacle,subjecting the mixture in said receptacle to a temperature sufficient tobreak any emulsion which may exist and tend to permit at least someagglomeration of the soap stock particles, subjecting the heated mixtureto mild mechanical agitation sufficient only to prevent the same fromgravitational settlement, whereby to constantly maintain said body ofthe mixture in a condition for centrifugal separation, continuouslywithdrawing through a relatively small conduit a stream of the thusconditioned mixture V from the vessel and introducing it to acentrifugal separator, and centrifugally separating the soap stock fromthe refined oil while at a suflicient temperature to facilitate suchcentrifugal separation.

7. The process of refining animal and vegetable oils which comprises thesteps of introducing an alkaline refining reagent to said oils whilesubjecting the same to relatively intense agitation and under such lowtemperature conditions as to favor the formation of an emulsion, wherebyto rapidly neutralize the free fatty acids and form soap stock,maintaining a relatively large body of said emulsion in a relativelylarge stirring vessel, applying heat to said vessel to an extentsuflicient to break said emulsion while subjecting the same to stirringaction of a relatively less intense character and sufiicient only tocreate a turbulence to maintain the foots uniformly distributed in theoil while avoiding turbulence in excess thereof, thereby to constantlymaintain a body of the mixture conditioned for centrifugal separationand for a time sufiicient to cause the breaking of the emulsion whilecontinuously discharging a stream of said mixture from the vesagitatingthe conditioned mixture at a rate sufficient only to maintain the soapstock particles in an evenly dispersed condition and preventing thegravitational settlement thereof, continuously withdrawing a stream ofthe mixture, while continuing the said agitation, and introducing thesame to a centrifugal separator at a temperature sufficient tofacilitate such separation.

9. The process of refining vegetable oils of the cold pressed type whichcomprises the steps of admixing with such oils an alkaline refiningreagent, substantially in excess of the amount theoretically required toneutralize the free fatty acids contained in such oils and to form soapstock, breaking any emulsion which may form timing the mixing of thealkaline reagent and the oils, delaying the time of contact of thealkali with said oils by maintaining a relatively large volume of themixture in a relatively large receptacle for a period of time sufficientto remove the color impurities of said oil, continuously withdrawingfrom said relatively large receptacle said admixture in the thus treatedcondition and subjecting the same to centrifugal separation to separatethe soap stock and combined color impurities from said oils andemploying sufiicient temperature at the time of such separation tocondition the mixture for separation.

10. A process of refining animal and vegetable oils containing freefatty acids which comprises mixing an alkaline refining reagent, in anamount in excess of that theoretically required to neutralize said freefatty acids, with said oil, and forming an emulsion containing soapstock, continuously introducing into a relatively large chamber a streamcontaining said emulsion, maintaining said mixture in said chamber for asuflicient time and at sufficient temperature to substantially breaksaid emulsion and substantially reduce the color by reaction between theexcess refining reagent and the color impurities, continuouslywithdrawing a stream of said mixture and introducing the same to acentrifugal separator and effecting separation of the soap stock fromthe oil while the mixture is at a temperature sufficient to facilitatesuch separation.

11. A process of refining animal and vegetable oils which comprises thesteps of mixing, in stream flow, mechanically metered and properlyproportioned streams of oil and a saponifying reagent whereby to effectsubstantial neutralization of the free fatty acids contained in said oiland the formation of soap stock, subjecting the mixture to a temperaturesufiicient to facilitate centrifugal separation, accumulating in arelatively large vessel a relatively large volume .of said mixture whilesubjecting the same to such a state of movement as to condition the soapstock for centrifugal separation, continuously withdrawing the mixtureof soap stock and.oil from the relativeLv large vessel and introducingthe same to a centrifugal separator and there effecting separation ofthe soap stock while the mixture isat a temperature sufficient tocondition the same for such separation.

12. The process of refining animal and vegetable oils which comprisesthe steps of adding an alkaline reagent to the oils to neutralize thefree fatty acids and form soap stock, conditioning the mixture forcentrifugal separation with the aid of heat sufficient for that purpose,and thereafter subjecting ,a relatively large body of the mixture, in arelatively large vessel, to mechanical agitation sufficient to maintainthe soap stock in a condition for treatment by the centrifugalseparator, continuously withdrawing a stream of said mixture, whilecontinuing said agitation, and introducing the same to a centrifugalseparator and there effecting continuous separation of the soap stockfrom the oil while the mixture is at a temperature sufficient tocondition the same for such separation.

13. In the art of removing free fatty acids and coloring material fromanimal and vegetable oils wherein proportioned streams of oils and analkaline refining reagent are admixed and subjected to an emulsionbreaking temperature, the improvement which comprises delivering astream of said mixture at said emulsion breaking temperature to a colorreduction zone of relatively large capacity whereby the rate of movementof said stream is reduced and the period of contact prolonged in orderto render color impurities separable with the soap stock, andcentrifugally separating said soap stock along with color impuritiesfrom said oil while said mixture is conditioned for said centrifugalseparation.

14. The process of refining relatively "slow breaking" oils whichcomprises the steps of mixing proportioned streams of an alkalinerefining reagent and said oils to effect substantial neutralization ofthe free fatty acids therein contained and to form soap stock,delivering the mixture, at an emulsion breaking temperature, to aconditioning zone of relatively large capacity and prolonging the timeof contact between the oil-and alkali for a suiilcient period of time toinsure the breaking of any emulsion which may persist in said admixturewhereby to condition the mixture for the act of centrifugal separationand thereafter subjecting the mixture to centrifugal separation while ina condition facilitating such separation.

15. In the art of continuously removing free fatty acids and colorimpurities from animal and vegetable oils comprising the steps of mixingan alkaline refining reagent with said oils to substantially completelyneutralize the free fatty acids contained therein and to form soapstock, conditioning the mixture for the step of centrifugal separationwith the aid of heat suificiently high to break any emulsion which mayresult from said admixing, advancing the thus broken emulsion of oil andsoap stock through a color reduction zone of relatively large capacitywhereby to decrease the rate of fiow therethrough and there maintainingit for a period sufiiciently long to permit color reduction, preventingthe continued rise in temperature of the mixture as it passes throughsaid color reduction zone by discontinuing the application of heatthereto whereby to minimize refining losses during the color reductionstep and thereafter introducing the mixture to a centrifugal separatorand continuously separating the soap stock and color impurities from therefined oil while the same is in a condition facilitating suchseparation.

16. In the art of removing free fatty acids and coloring material fromanimal and vegetable oils comprising the steps of mixing proportionedstreams of oil and an alkaline refining reagent to effect neutralizationof the free fatty acids contained in the oil and to form soap stock,breaking any emulsion which may exist as a result of said mixing withthe aid of heat sufficient for that purpose, whereby to condition themixture for the act of centrifugal separation, thereafter continuouslydelivering a stream'of the thus broken emulsion to a color reductionzone of relatively large capacity whereby the rate of movement of saidstream is reduced and the period of contact prolonged for a sufiicienttime to permit the softened soap stock particles to combine with colorimpurities to effect substantial col'or reduction of said oil andthereafter centrifugally separating the soap stock with the combinedcolor impurities from said oil under such conditions as will permit suchseparation.

17. In the art of purifying animal and vegetable oils containing colorimpurities comprising the steps of admixing proportioned streams of analkaline refining reagent and said oils to effect substantialneutralization. of the free fatty acids contained in said oils and toform soap stock, conditioning the mixture for centrifugal separationwith the aid of an emulsion breaking temperature, thereafter advancingthe broken emulsion of oil and soap stock through a color re-. ductionzone of relatively large capacity wherein the same is maintained for -aperiod of time willciently long to permit color reduction by slowingdown the rate of travel of the mixture as it passes through said zoneand continuously separating the soap stock particles and the combinedcolor impurities from the refined oil while the mixture is in acondition permitting such separation.

18. A process for refining glyceride type oils to remove impurities suchas free fatty acids and color impurities, which process includes thesteps of forming a mixture of proportioned quantities of said glyceridetype oil and an alkaline refining reagent capable of reacting veryrapidly with said free fatty acids to form foots and used in excess ofthat amount theoretically required to complete reaction with the freefatty acids, the excess being available for reaction with said colorimpurities to produce a mixture containing oil, foots, color impuritiesand the excess of said refining reagent; introducing said mixture into arelatively wide stirring chamber and therein maintaining a relativelylarge volume thereof under such conditions of turbulence to maintain thefoots uniformly distributed in the oil while avoiding turbulence inexcess thereof and for a sufficient time and at a sufiicient temperatureto condition the mixture for the act of centrifugal separation and toeffect substantial color reduc-' tion; flowing a stream of thisconditioned mixture into a zone of centrifugal separation; separatingthe foots from the oil and applying additional heat to the footssufilcient to facilitate their discharge from the centrifugal machine.

19. A process for refining glyceride type oils to remove impurities suchas free fatty acids and color impurities, which process includes thesteps of: forming a--mixture of proportioned quantities of saidglyceride type oil and an alkaline refining reagent capable of reactingvery rapidly witlrsaid free fatty acids to form foots and used in excessof that amount theoretically required to complete reaction with the freefatty acids, the excess being available for reaction with said colorimpurities to produce a mixture containing oil, foots, color impuritiesand the excess of said refining reagent; introducing said mixture into arelatively wide stirring chamber and therein maintaining a relativelylarge volume thereof under such conditions of turbulence to maintain thefoots uniformly distributed in the oil while avoiding turbulence inexcess thereof and for a sufficient time and at a sufiicient temperatureto condition the mixture for the act of centrifugal separation and toeffect substantial color reduction; fiowing a stream of this conditionedmix- .ture into a zone of centrifugal separation; and there, separatingthe foots from the oil at a temperature facilitating such separation.

20. The process of refining fatty oils which comprises the stepsofmixing said oils with an alkaline refining reagent in a mixing zone,preheating at leastone of the materials before the admixture thereof,thereafter delivering the mixture to a zone of relatively large crosssection as 7 compared with said mixing zone and therein decreasing thevelocity of the mixture and prolonging the time of contact of saidmaterials while under such a temperature and state of movement as topermit agglomeration of the soap stock resulting from the reaction ofthe alkaline refining reagent with said oils while avoiding such rapidagitation as would produce a centrifugally inseparable colloidalsuspension and thereafter centrifugally separating the soap stock fromthe refined oil while the mixture is in a condition facilitating suchseparation.

21. The process as defined in claim 20 in which the application ofsubstantial additional heat is avoided while the mixture passes throughsaid zone.

22. The "continuous process of refining fatty oils which comprises thesteps of mixing an alkaline refining reagent with said oils in a mixingzone, maintaining a relatively large volume of said mixture in arelatively large receptacle as compared with said mixing zone to prolongthe time of contact of said. materials whereby to increase the time forthe reaction of the materials comprising said mixture, thereby to permitthe employment of a relatively low temperature 'dur-. ing said reaction,maintaining the mixture in -said relatively large receptacle in such astate of agitation as will prevent stratification of the t ts resultingfrom said reaction and continufatty acids, gums and coloringmatter, aprocess which comprises the steps of pumping together in generallyangular directions relatively small metered streams of oil and analkaline refining reagent in substantially constant predeterminedproportions, preheating at least one of said materials prior tocontacting the same, advancing said materials from their point ofcontact to the upper portion of a relatively large open receptaclewhereby to decrease the velocity of the mixture passing downwardlythrough said receptacle to prolong the time of contact of saidmaterials,

avoiding the application of additional heat to said receptacle as themixture passes therethrough whereby to reduce refining losses, maintaining a state of movement sumcient to prevent stratification of thematerials in said receptacle, continuously withdrawing a relativelysmall stream of the mixture from said relatively large receptacle,raising the pressure on said stream to force the same to a centrifugalseparator whereby a substantially constant supply to said centrifugalmay be maintained.

25. The process as defined in claim 24 in which additional heat isapplied to the soap stock to facilitate its discharge from saidcentrifugal separators.

26. The process of refining fatty oils which comprises the steps ofmixing an alkaline refining reagent with said oils in a mixing zone,preheating at least one of said materials before the admixture thereof,minimizing the temperature required for eflecting the precipitation ofsaid impurities by continuously introducing the mixture to a relativelylarge receptacle as compared with said mixing zone whereby to decreasethe velocity thereof and prolong the time of contact of the materialscontained in said admixture, while maintaining the mixture as it passesthrough said relatively large receptacle in a state of agitationsufiicient to prevent stratifica tion of the foots therein whileavoiding such rapid agitation as would produce a centrifugallyinseparable colloidal separation, continuously withdrawing the mixturefrom the receptacle and centrifugally separating the foots from therefined oil while the mixture is in a condition permitting suchseparation.

2'1. The process as defined in claim 28 in which the discharge of thesoap stock is facilitated by applying additional heat thereto.

28. In the purification of fatty oils containing impurities includingfree fatty acids, gums and coloring matter, a process which comprisesthe steps of pumping together in generally angular directions relativelysmall metered streams of oil and an alkaline refining reagent insubstantially constant predetermined proportions while excluding thepresence of air, preheating at least one of said materials prior tocontacting the same, advancing said materials from their point ofcontact to a relatively large receptacle whereby to decrease thevelocity of the mixture passing through said receptacle to prolong thetime of contact of said materials for at least several minutes, avoidingthe application of substantial additional heat to the mixture as thesame passes through said receptacle whereby to reduce refining losses,maintaining a state of movement sufficient to prevent stratification ofthe precipitated foots in said receptacle while avoiding such violentagitation as would produce a centrifugally inseparable colloidalsuspension, advancing, under superatmospheric pressure, a stream of themixture from said receptacle to a zone of centrifugal separation andthere separating the foots from the mixture while correlating the rateof centrifugal separation with the rate of pumping of said streamswhereby the mixture is caused to remain in said receptacle for apredetermined period of time.

BENJAMIN H. THURMAN,

